Introduction

NVMe (Non-Volatile Memory Express) technology is transforming SSD's as we know them. For now, NVMe operates over PCIe interfaces. NVMe is designed to be future proof, with a protocol built for current and future non-volatile storage solutions such as PCM (Phase Change Memory) or MRAM (Magnetoresistive Random Access Memory) memory. Currently there are two competing solutions; one offered by Intel and the other offered by Samsung. The two companies have taken vastly different approaches to delivering a consumer based NVMe storage solution.

Intel's approach is a full size and full power (up to 25 watts) desktop solution. Intel's 750 PCIe Gen3 8Gb/s x 4 Lane series SSD's are available in two form factors, a full size HHHL AIC (Half Height Half Length Add-In-Card) PCIe slot SSD or a 2.5"x 15mm SSD with an 8639-compatible connector. Intel went full size as opposed to an M.2 form factor to avoid incurring limitations that are inherent to a device that is so small. Intel's 750 series SSD's are loaded up with a total of 36-20nm planar flash packages, 5-DRAM packages and a massive 18 channel controller.

Samsung has taken an opposite approach by embracing the M.2 form factor despite its diminutive size. In contrast to Intel's 750 series, Samsung's 256GB SM951 PCIe Gen3 8Gb/s x 4 Lane NVMe M.2 SSD has only 2-16nm Planar flash packages, 1-DRAM package and a proprietary UBX 3-core 8-channel controller. The SM951 is designed primarily for implementation in today's ultra-slim notebook PC's that require extended battery use. To extend battery life, the SM951 is capable of L1.2 low-power standby mode, which allows all high-speed circuits to be turned off when a PC is in sleep mode or hibernating, requiring only 2mW to maintain operational status. Currently Samsung's SM951 NVMe M.2 SSD is only available to OEM's, however RamCity has stated to us they will be selling the drive to consumers beginning in mid-July of this year.

We are starting to see many enthusiasts using the AHCI SM951 in their desktop's Ultra M.2 slots as a boot drive. Despite its small size, the SM951 AHCI SSD is 4x faster than SATA-based SSD's and in a desktop setting delivers performance nearly on par with Intel's 750 Series NVMe SSD's. Samsung is looking for the performance crown and in an effort to capture it, they have introduced an NVME version of their highly successful SM951 M.2 SSD. The NVMe protocol has a greatly reduced command stack that delivers lower latency, higher IOPS and reduced CPU overhead, so we expect to see great performance from Samsung's SM951 NVMe SSD.

We will examine both how the SM951 NVMe stacks up against Intel's monster 750 Series, as well as how much better it performs in comparison to the SM951 AHCI version. When we last looked at the SM951 AHCI SSD, we had a Lenovo version that did not deliver full performance. Today we have one that does deliver full performance and we will be charting its performance alongside the new SM951 NVMe drive. As points of comparison, we will also be charting a powerful 3-drive Seagate 600 Pro SATA array, Intel's 750 Series 1.2 TB NVMe SSD and Intel's DC P3700 800GB enterprise NVMe SSD.

As most of you know, we believe that providing results with the drives running as our boot volume 75% full is far more relevant than providing you with results from empty SSD's in an FOB state. Testing boot volumes also allows us to comment with authority on how the drive/array handles when used as you will be using it. This method of testing takes more time and effort, but we believe it is well worth it.

Let's get going and see for ourselves what level of performance can be expected from a Samsung SM951 NVMe 256GB SSD.

Specifications Samsung SM951 NVMe 256GB

Samsung's SM951 NVMe SSD is available in three capacities: 128GB, 256GB, and 512GB. Sequential read performance varies by capacity up to 2150 MB/s maximum. Sequential write performance varies by capacity up to 1550 MB/s maximum. The drive delivers up to 300,000 Random Read IOPS and 100,000 Random Write IOPS. LBA addressing is handled by a single Samsung DRAM package at all three capacity points. TBW (Total Bytes Written) and warranty period is unknown.

Power consumption is listed at 6.5W (typical) active. Idle power consumption is listed at 50mW (typical). Device Sleep power consumption is listed at 2mW.

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